Hi,
What is the purpose of it? Corona is as fast as it can possible be, without compromising the quality and accuracy of physical phenomenons.
If there was a way to make it faster through invisible ray-switch setup, it would have already been there.
If you want to make rendering faster, for a specific scene, it is better to understand what are the problematic parts in the scene, causing the slowdown.
From what you are saying, I think you can try RaySwitch in material override slot, can't you?